A. Field of the Invention
The present invention relates to an apparatus and method of conveying grain from at or near the bottom of a grain bin, and particularly to such a method and apparatus which handles the grain more gently then conventional methods but efficiently withdraws grain from at or near the bottom of it to outside the bin for further use.
B. Problems in the Art
A variety of ways and structures have been devised to temporarily store grain or seed and selectively remove it from storage. One well-known method uses a circular sheet metal bin extending from a concrete slab generally at or near ground level. Typically, a metal floor is supported about a foot or so above the top of the slab. It can be perforated to allow passage of air but not the grain to be stored. A conical roof covers the cylindrical bin to protect it from the elements. Frequently there are vents added near the top of the bin and a fan added to the bottom of the bin. The fan draws air through the vent, and the bin, and the stored seed in the bin, and out the exhaust fan. This allows for aeration of the stored grain.
These bins can vary in size. Examples can be on the order of 20 feet in diameter and 20 feet tall, to several times that size. They represent a generally economical structure that can handle the weight and forces of a substantial quantity of grain (thousands of bushels) and both protect and allow it to be maintained in quality for further use and processing.
However, removal of grain from such a structure is not a trivial task. Competing interests are at stake. It is normally desirable to have an unloading system that has relatively high throughput to save unloading time. On the other hand, it is generally desirable that such a system be non-complex and relatively low cost. A conventional way of unloading such bins utilizes an auger placed laterally along the bottom of the bin between the slab and the metal floor. It extends outside the bin through an opening in the sidewall at or near the foundation slab. There sometimes is a channel or void in the slab in which the auger sits. Corn falls by gravity into the auger, usually through an opening in the metal floor. When removal is needed, the auger is simply operated. Normally the auger feeds the grain externally of the bin. Some other device then must be communicated with the outside end of the auger to lift it or otherwise convey it for further use.
Such a system is advantageous because it uses relatively simple mechanical devices and structures. It also utilizes gravity as the primary force to feed the grain to the auger. There may be manual labor involved to completely move all the grain from the bin (particularly once gravity no longer moves into the auger), but it avoids having some type of mechanism to move the grain vertically out of the bin.
However, certain deficiencies have been recognized with this type of system. For example, augers tend to grind or split at least some of kernels of grain. This not only can engender mechanical problems, e.g. jamming or degradation of the auger or structure around the auger, it can destroy or damage the grain. This is an increasingly important issue in today's agriculture. Plant science has evolved to develop varieties of seed or grain with special properties that are highly valued. However, the value can be dependent on the seed being intact and not materially damaged. One example is what is sometimes referred to as high oil grain. This is highly valued, for example, by food processors. However, the amount paid for the grain is dependent on its quality. Conveyance by augers tend to be detrimental on this point. Another example is what is called pharming or nutraceuticals. Genetic engineering is allowing pharmaceutically-active substances to be developed in growing seeds, including corn and soybeans. Once harvested, those active components are extracted by highly specialized processing. Again, the value of the grain is dependent on its quality. Damage in handling from harvest to processing must be minimized. Thus, the price for a grain crop can be highly dependent on amount of damage to it between harvesting and sale of the grain. In fact, many times grain will not even be accepted by a commercial buyer unless it meets certain minimum quality standards. On the other hand, a premium price will be paid for grain exceeding certain standards.
Therefore, a real need in the art has been identified for improving the quality of grain between storage and removal from a storage bin.
Secondly, state of the art augers are frequently required to be installed permanently at or in the concrete base of the bin. This not only adds to the cost of the bin when it originally constructed, but also dedicates that auger to that single bin. It cannot be selectively removed and used for other purposes, such as when unloading other bins.
Third, augers have inherent safety issues. Sufficient power must be imparted to the auger to move a substantial mass of grain. The auger flightings must conform closely to a housing. This configuration can grab or pull on clothing and is dangerous to the extremities of workers around it.
Therefore, auger unloading systems have further issues that have not been adequately addressed in the art.
Another type of current grain bin unloading methodology utilized vacuum. Negative pressure is generated at the end of a conduit outside the bin. A distal end of the conduit is inserted in the bin or at or near the bottom of the bin. Gravity can be used to move grain to that distal end and vacuum would convey it through the conduit to outside the bin. However, to attain high enough throughput, relatively high vacuum must be created. This takes significant energy and equipment, which makes them relatively expensive. Secondly, vacuum may cause some of the grain to impact along the interior of the conduit which could damage the grain and reduce its quality. Further, grain-to-grain impact while fluidized and moving in the conduit can also reduce quality.
Therefore, a real need for the improvement in the art of unloading grain bins has been identified.
One example of another type of grain bin unloading apparatus is shown at U.S. Pat. No. 5,088,871 to Mellish. Mellish shows a conveyor system having an elongated horizontal section and then an inclined section. The horizontal section is insertable into a concrete channel that extends across the diameter of a grain bin. A door is coincident with one end of the channel. This system is alleged to be useful to move horizontally out of the bin grain that is gravity-fed onto the top of the conveyor (see Mellish, FIG. 2). The inclined portion allows grain to be raised off ground level and dropped into another device for further conveyance. However, similar to an auger, the grain is exposed to moving metal that can damage it. Mellick uses exposed chains and metal angle iron cross pieces to pull the grain horizontally along a surface and then up the incline. This would also traumatize and/or damage grain, perhaps more so than an auger, and therefore would not solve the identified problems and deficiencies in the art.